what list comprehension can't

ajikoe

Hello,

Can we impose if then else into list comprehension ?
Like we do in lambda-map form:

This code change None into 0
L = [None, 12]
R = map(lambda x: (x==None and [0] or x)[0], L) # [0,12]

pujo

Jul 19 '05 #1

Devan L

I wasn't aware that python supported "if then else".

Jul 19 '05 #2

Christophe Delord

Hello,

On 24 Jun 2005 11:45:14 -0700, aj****@gmail.com wrote:

Hello,

Can we impose if then else into list comprehension ?
Like we do in lambda-map form:

This code change None into 0
L = [None, 12]
R = map(lambda x: (x==None and [0] or x)[0], L) # [0,12]

Do you mean:
[(x==None and [0] or [x])[0] for x in L]
or [{None:0}.get(x,x) for x in L]
or [x or 0 for x in L]

Well, the third solution doesn't exactly fit the specification but may
be easier to read.
Christophe

Jul 19 '05 #3

ajikoe

Thank you

pujo

Jul 19 '05 #4

Steven D'Aprano

On Fri, 24 Jun 2005 21:04:15 +0200, Christophe Delord wrote:

Hello,

On 24 Jun 2005 11:45:14 -0700, aj****@gmail.com wrote:

Hello,

Can we impose if then else into list comprehension ?
Like we do in lambda-map form:

This code change None into 0
L = [None, 12]
R = map(lambda x: (x==None and [0] or x)[0], L) # [0,12]

Do you mean:
[(x==None and [0] or [x])[0] for x in L]
or [{None:0}.get(x,x) for x in L]
or [x or 0 for x in L]

Well, the third solution doesn't exactly fit the specification but may
be easier to read.

Or, more generally,

[0 for x in L if x is None]

which doesn't solve the asked-for question, but is a useful feature.
--
Steven.

Jul 19 '05 #5